Electromagnetic radiation (EMR) is emitted by every operating electric and/or electronic device. The power of EMR emission varies depending on the size and electrical strength of the device and the electrical current it carries or employs. In addition, unwanted currents on input and output cables to and from an electronic device may cause the cables themselves to become sources of undesirable EMR. EMR is problematic since it may interfere with components of electronic devices located in the vicinity of the source of EMR, causing electromagnetic interference (EMI). It is known that electronic components or products and devices in the vicinity of EMR sources may malfunction if subjected to certain levels of EMI. EMI generated and received by electronic devices must be attenuated not only to keep the devices functioning properly but also to bring the devices into compliance with applicable governmental regulations. In the United States, the Federal Communications Commission (FCC) promulgates regulations to limit the amount of radiation emitted from electronic equipment, and to provide for routine testing of manufactured products to ensure compliance. Similar administrative bodies perform the same function in Canada, Europe and other parts of the world.
One known solution used to contain or reduce unwanted EMR from products containing electronic devices is through the use of shielded cables. Unfortunately, shielded cables are expensive compared to unshielded cables. Shielded cables also contain a larger form factor, thus occupying much more space within a product enclosure. In addition, the integrity of shielded cables can be more easily compromised as the cables are flexed or moved because they are not as flexible as unshielded cables and the use of unshielded cables facilitates ease in manufacturing.
Another solution to contain or reduce unwanted EMR from products containing electronic devices is to place the equipment in encompassing metal enclosures. The encompassing conductive enclosure forms a Faraday shield which reduces radiated power by forcing the electric field component of an electromagnetic wave to be nearly zero at the surface of the conductor, thereby blocking wave propagation. Unfortunately, emissions through necessary openings in the enclosures for outputting signals, lessens the effectiveness of the enclosures. Additionally, the resulting package is bulky and relatively expensive.